These are some mistakes that are seen very regularly in contributions - pay special attention that you are not including these in your contributionssubmissions:
Invalid UPCs
Incorrect Locality used - Changing content to a different Locality version of a DVD, without changing the Locality itself.
Incorrect Currency used for the Locality contributed.
Overwriting data with changed information of re-releases (case type, cover images, SRP,...)
Overwriting data with cover information which are proven to be false (running time, Region Codes,...) ->Read previous contribution notes